so i have a html page with a body and the following structure
<body>
    <h1>Hello</h1>
    <div>
        <div>
            // editable area -->
            <div id="b">
                <h1>Bye</h1>
            </div>
            // <--
        </div>
    </div>
</body>
I want to style the <body> but can only access and edit the <div> with id "b" and add a custom css file. Since  the css file is used for more than one html files i can't just directly style the <body>.
Is there a possibility to style a <body> with a specific child element (child of a child) with a specific id?  
 
     
    